My friend would start shaking all over whenever she went up to the stage, be it to deliver a speech or announce something or even to collect a prize.
There is nothing wrong in feeling nervous before going on stage. It is perfectly normal. Everyone faces it some time or the other.
First of all, the fear is only in the mind. So relax your mind before it is time for you to go on-stage. Sachin Tendulkar had mentioned in an interview some time back that he copes with the nervousness of play by listening to music till it is time for him to go out to play.
You too may do this, stop dwelling in the nervousness and divert your mind till it is time for you to go onstage. This will help to decrease your fear.
Secondly, the fear may arise due to lack of confidence in yourself. This can be remedied by practising thoroughly the speech or item which you are going to deliver. Practise your speech or item scores of times with your family/friends as an audience. You could also stand before a mirror and watch yourself speak.
Thirdly, the fear may be because of the large number of people that you have to face. For this you should remember that the people who are listening to you are normal human beings like you and are not ogres out to devour you and put in a similar position they too would be nervous. So why fear a bunch of people who themselves are scared?
How can you cope with the fear of darkness? Not by switching on the light or running away from it; this way you can never rid of your fear for it. The only way to get rid of your fear of darkness is by being with it. You get over the fear of darkness by becoming aware of all the familiar objects in the room and realizing that they are not demons waiting to get you! Be in the dark and you will start overcoming your fear of it. In the same way, to get rid of your fear of stage, keep doing what you fear again and again and gradually your fear will disappear.